Interface Co‐Assembly Synthesis of Magnetic Fe₃O₄@mesoporous Carbon for Efficient Electrochemical Detection of Hg(II) and Pb(II)

Abstract

Hg(II), Pb(II), Cd(II), and As(II)) cannot be degraded in the environment (viz. water and soil). [1][2][3][4] Therefore, considerable efforts have been focused on the development of highly sensitive and remarkably selective sensors, which can permit rapid measurement, for monitoring heavy metals in the environment. Currently, various analytical methods have been applied for the detection of HMIs, such as inductively coupled plasma mass spectrometry, [5] inductively coupled plasma atomic emission spectrometry, [6] and atomic absorption spectrometry. [7] However, these methods require high-cost instruments and tedious operation steps, which are not conducive to the real-time monitoring of heavy metal ions in the environment. As a classic and commonly used analytical method, electrochemical sensors have attracted increasing attention for the detection of HMIs due to their high sensitivity, rapid response, and facile assembly into portable devices. [8][9][10] Meanwhile, anodic stripping voltammetry, especially the differential pulse anodic stripping voltammetry (DPASV), is one of the most commonly used methods for the determination of trace heavy metal ions due to its excellent sensitivity and selectivity. The sensor performance of this method mainly relies on the reduction-oxidation of metal ions at the interface between In recent years, efficient and porous carbon-layer-modified magnetic metal oxides demonstrate potentials for the significant improvement of catalytic and adsorption performance. In this study, a novel magnetic coreshell Fe 3 O 4 @mesoporous carbon (Fe 3 O 4 @MPC) nanochain electrochemical sensor is constructed by using resorcinol-formaldehyde resin and magnetic Fe 3 O 4 nanospheres as the carbon shell precursor and core, respectively, with a simple emulsion self-assembly strategy. Microstructural characterizations revealed that the carbon shell exhibited a mesopore distribution of ≈40 nm and the diameter of Fe 3 O 4 nanospheres embedded into carbon is ≈280 nm. The introduction of mesoporous carbon layer increased the electrical conductivity of the active material and maintained the adsorption properties of magnetic Fe 3 O 4 . The synergistic effect of the mesoporous carbon layer and Fe 3 O 4 nanochain is beneficial to electrochemically detect heavy metal ions (HMIs). Under optimal conditions, the typical Fe 3 O 4 @MPC-2/GCE exhibited excellent electrochemical sensing for detecting Hg(II) and Pb(II), with limits of detection (LOD) of 7.8 nm and 12.1 nm (S/N = 3), respectively. These good results are attributed to the Fe 3 O 4 @MPC nanochain structure and a relatively high specific surface area. This study provides a novel method to prepare magnetic mesoporous carbon nanochain composites for constructing sensitive electrochemical sensors to monitor water quality.

Alkaloid Precipitant Reaction Inspired Controllable Synthesis of Mesoporous Tungsten Oxide Spheres for Biomarker Sensing

“…In order to prove this APR process, other polymer spheres were also used to interact with HPW. For example, mesoporous resorcinol-formaldehyde resin spheres with radially oriented mesochannels (mRF-R) synthesized via the previously reported method show poor capability in inducing the precipitation of HPW species, 54 and only P-doped WO 3 fragments were obtained after calcination (Figure S7a,b). It is due to the weak interaction between HPW and hydroxyl groups that hindered the above process (Scheme 2).…”

Review—Recent Advances in Electrochemical Sensing of Lead Ion

“…Meanwhile, iron-based oxides were also frequently used to detect Pb 2+ due to their abundant sources, excellent biocompatibility, high catalytic activity, and can significantly improve the catalytic and adsorption properties of composites. 68 For example, Liu et al 69 employed a simple self-assembly strategy to construct a novel magnetic core-shell Fe 3 O 4 @mesoporous carbon (Fe 3 O 4 @MPC) nanochain electrochemical sensor for the detection of Hg (II) and Pb (II). Due to the excellent adsorption properties of magnetic iron oxide and the synergistic effect of mesoporous carbon layer and Fe 3 O 4 nanochains, the Fe 3 O 4 @MPC modified electrode exhibited a good linear response range and low LOD (12.1 nM).…”

Constructing Fe2O3 nanoparticles in nitrogen-doped carbon materials to enhance the electrochemical sensing performance of Pb2+ and Cd2+

“…Adding different amounts of NH 3 •H 2 O could regulate the interface assembly process so as to adjust the content of N and its electronic state on the material surface to make it reach the best electronic state. 33,34 Therefore, taking full advantage of the adsorption properties of Fe 2 O 3 NPs and the high electrical conductivity of N-doped carbon materials together, the synergistic effect of the two can enhance the effectiveness of detecting HMIs with Fe 2 O 3 @NCNPs-x nanocomposites. In this study, the conductivity of materials was improved by regulating the defects of Fe 2 O 3 NPs, providing the possibility of improving the detection ability of HMIs with Fe 2 O 3 NPs.…”